The invention relates to the field of data, processing, and particularly, relates to a method and apparatus for transforming web service policies from logical model to physical model, and a method and system for generating a physical service and policy model of a service-oriented architecture (SOA) system.
As web service applications have become more complex, the first generation web service architecture no longer adequately accommodates development requirements for current web services. Thus, a Service-Oriented Architecture (SOA) has been proposed. SOA establishes the concept that a web service system may be composed of a series of sub-systems or services that are separate but that cooperate with each other. Such a structure enables the services to be separated. Each service needs only inform other services of its declared interface. Therefore, SOA allows corporation business flows to be created that are only loosely coupled. Where SOA concepts are used, a web service system may be formed by web services executed in remote and different domains, replacing the conventional hierarchical structure of a system with service flows across various business areas.
In order to satisfy a user's requirements for quality of service, a SOA system should comply with a Service Level Agreement (SLA) that defines the level of service expected by the user. Web service policies are used to describe the requirements and abilities of a web service in its interactions with other web services or consumers and are important in setting up Service Level Agreements.
The Web Services Policy Framework (WS-Policy) defined by IBM, BEA, Microsoft and others is the de facto standard for Web Services policy. It provides a common model and corresponding syntax to describe policies of a web service. WS-Policy is intended to allow for extensibility. That is to say, WS-Policy defines a base set of constructs that can be used and extended by other web services specifications to describe a broad range of service requirements and capabilities (the non-functional part). Base on WS-Policy, a set of standards have been defined for different perspectives of a system, including Web Service Reliability Messaging Policy (WS-RM Policy), Web Service Security Policy (WS-Security Policy). Web Service Atomic Transaction (WS-AtomicTransaction), Web Service Policy Assertions (WS-PolicyAssertions), etc. Users can also define policy languages based on WS-Policy and related standards for their needs.
The current WS-Policy definition tool, however, is not ideal and has at least the following drawbacks:                1. It focuses on a single set of policy assertions attached to the policy subject and does not take the impact of system context into consideration;        2. The policy subject is limited to service level and below granularities such as service, port, operation, and message;        3. It does not support top-down SOA system design methodology from abstract level to physical level and lacks an automation tool for policy transformation and deployment;        4. Policy allocation and consistency validation of related policy subjects is postponed to runtime, when the reallocation or reconfiguration becomes more inflexible and expensive.        